Rolled out a month or so back, Express Pay was only in Local 1996 Atlanta and might still be.  You can sign up and get paid for some portion of the hours you already worked that week as recorded in the time clock.  

It's not an advance. You don't pay it back. You just get paid early. The remaining balance is paid out on the next pay check.  So if you already worked 24 hours and use Express Pay to get 12 hours worth of pay, you'd get the other 12 hours of pay on your next payday.

There are limits on how much you can get and it has to be during the same week so if it's Sunday you have to wait for your regular payday, you can't go back and get money from the previous week.